‘Stage set’ for large trials to widen leukaemia and lymphoma donor pool

Two new US clinical trials suggest more patients with leukaemia and lymphoma could benefit from bone marrow transplants if half-matched bone marrow or unrelated umbilical cord blood were used.

A donor’s tissue usually has to be a full match with the recipient’s tissue in order for a transplant to go ahead.

This means that many patients who need a transplant are unable to find a suitable donor.

But two new phase-II trials suggest that a donor’s tissue need not fully match that of the recipient for a transplant to be successful.

More research is needed, as these were relatively small studies, but the findings suggest that many more patients who need this type of transplant could be able to find a suitable donor in the future.

In the latest clinical trials, researchers from the Blood and Marrow Transplant Clinical Trials Network in the US tested the viability of 50 half-matched or ‘haploidentical’ bone marrow transplants and 50 unrelated cord blood transplants in adults with advanced leukaemia or lymphoma.

They found that 54 per cent of cord blood transplant recipients were still alive after one year and 46 per cent showed no signs of disease progression.

Meanwhile, 64 per cent of patients who received half-matched bone marrow survived for at least one year, and 48 per cent had no disease progression.

According to the researchers, whose findings are published in Blood journal, these survival rates are similar to those seen in patients who receive fully matched donor tissue.

None of the participants developed severe graft versus host disease (GVHD), which can occur if the donor’s immune cells start to attack the patient’s own healthy tissues.

This was particularly noteworthy considering half of the patients involved in the trials were 50 or older – an important risk factor for GVHD.

Dr Ephraim Fuchs, a bone marrow transplant expert and professor of oncology at the Johns Hopkins Kimmel Cancer Centre in the US, welcomed the findings.

He pointed out: “Ten years ago, it was unthinkable to do a haploidentical transplant.”

The researchers are now planning a four-year clinical trial involving 380 patients, which should begin later this year or in early 2012.